Drugs, the Thyroid, and the Heart: A Lethal Cocktail

Published:October 26, 2018DOI:
      A 53-year-old man was referred for evaluation of a raised international normalized ratio blood result. He had been taking warfarin and amiodarone for 2 years following a transient episode of atrial fibrillation following a percutaneous coronary interventional procedure. He was receiving treatment for severe left ventricular systolic dysfunction and type 2 diabetes mellitus (Table 1). Initial evaluation revealed breathlessness at rest with evidence of decompensated cardiac failure (Figure 1), resting tremor, and no thyromegaly, and he was unable to stand unaided. Initial investigations confirmed a left pleural effusion, atrial fibrillation, acute kidney injury, deranged liver function tests, and a grossly elevated international normalized ratio (Table 2). The presence of severe biochemical hyperthyroidism in the absence of thyroid receptor–stimulating antibodies was determined. A diagnosis of type 2 amiodarone-associated thyrotoxicosis was made, and treatment with prednisolone and carbimazole commenced.
      Table 1Patient's Medication at Presentation
      Amiodarone 200 mg once daily Furosemide 40 mg once daily
      Warfarin 4 mg once daily Bisoprolol 5 mg once daily
      Irbesartan 150 mg once daily Gliclazide 80 mg twice daily
      Figure 1
      Figure 1Chest radiograph at initial presentation. Cardiomegaly and moderate left pleural effusion noted.
      Table 2Laboratory Test Results at Presentation with Thyrotoxicosis
      Blood Test Result
      Hemoglobin (g/l)

      NR (115-160)

      White cell count (x 109/l)

      NR (4.0-11.0)

      Platelets (x 109/l)

      NR (150-400)

      International Normalised Ratio

      NR (0.9-1.0)

      Free T4 (pmol/l)

      NR (10-20)

      Thyrotropin Stimulating Hormone (mU/l)

      NR (0.2–4.5)

      Thyrotropin Receptor Antibody (iu/L)

      NR (0-1.6)

      Creatinine (micromol/l)

      NR (60-120)

      C-reactive Protein (mg/l)

      NR (0-5)

      Lactate (mmol/l)

      NR (0.6-2.4)

      Albumin (g/l)

      NR (30-45)

      Urea (mmol/l)

      NR (2.5-6.6)

      HbA1c (IFCC) (mmol/mol)

      NR (10-50)

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